The time course of glucagon action on the utilization of [U-14C]palmitate by isolated hepatocytes |
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Authors: | Balbir Singh Harald Osmundsen Borgar Borrebaek |
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Institution: | Institute of Medical Biochemistry, University of Oslo, P.O. Box 1112, Blindern, Oslo 3, Norway |
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Abstract: | The time course of glucagon action on the utilization of U-14C]palmitate by isolated hepatocytes was studied. Ten minutes incubation of the cells after hormone addition was required in order to observe increased oxidation and decreased esterification of the labeled palmitate. The acid-soluble, labeled oxidation products could be separated into two main fractions, glucose and ketone bodies. Initially, glucagon directed the flux of radioactivity toward glucose and CO2. After prolonged incubation in the presence of glucagon, labeled ketone bodies, as well as labeled glucose and 14CO2, were increased. This effect was most marked as regards glucose. The results indicate that glucagon induces a rapidly onset stimulation of the rates of Krebs cycle and gluconeogenesis, while increased oxidation and decreased esterification of palmitate are time-delayed corresponding to the establishment of a lower level of glycerophosphate. About 10% of the glucose carbon formed by gluconeogenesis originated from the fatty acid when cells from fasted rats were incubated in the presence of alanine and U-14C]palmitate. |
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Keywords: | To whom all correspondence should be addressed |
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